1,3-Diphenyl substituted pyrazolines

ABSTRACT

1,3-Diphenyl substituted pyrazolines having, in the 4- or 5-position of the pyrazoline ring, a sulpho group in free acid or salt form, and the use thereof as optical brightening agents, particularly for synthetic polyamide.

The invention relates to sulpho group containing diphenyl pyrazolines.

Thus, according to the invention, there are provided optical brighteningagents, being 1,3-diphenyl substituted pyrazolines and having, in the 4-or 5-position of the pyrazoline ring, a sulpho group in free acid orsalt form.

Hitherto proposed sulpho group containing 1,3-diphenyl pyrazolineoptical brighteners have had the sulpho group or groups bound, directlyor indirectly, to the 1- or 3-phenyl substituents. We have now preparedcompounds in which the pyrazoline nucleus itself bears a sulpho group,which compounds in general posess relatively high substantivity andactivity, particularly when applied to nylon by the so-called "PadThermosol" procedure. The compounds also possess good solubility inwater.

The 1- and 3-phenyl rings of the compounds of the invention may, as willbe appreciated, be substituted, the nature of substituents which may beborne thereby being diverse, having regard to particular propertiesdesired of the compounds, e.g. shade of nuance when applied to thesubstrate to be brightened, degree of solubility etc. Such substituentsmay, for example, be those conventional in the art, i.e. not undulyaffecting the fluorescing properties of the compounds and/or theapplication of the compounds on the substrate to be brightened.Particular examples are given herein. Likewise, the available 4- or5-position (depending on the location of the sulpho group) of thepyrazoline ring may be substituted. Such position, however, ispreferably unsubstituted.

In the compounds of the invention, the sulpho group is preferably in the4-position.

Representative of the compounds of the invention may be given thecompounds which, in free acid form, are of formula I, ##STR1## in whicheither R₁, R₂ and R₃, independently, each signifies hydrogen, halogen,C₁₋₈ alkyl, C₁₋₄ alkoxy, cyano or --SO₃ H,

or two of

R₁, r₂ and R₃, together, signify a methylenedioxy radical, the otherhaving one of the above significances,

Or one of

R₁, r₂ and R₃ signifies a phenyl radical, unsubstituted or substitutedby one or two substituents selected from C₁₋₄ alkyl, C₁₋₄ alkoxy,halogen and --SO₃ H, the other two each having one of the significancesfirst mentioned above,

with the proviso that ring A bears no more than one substituent selectedfrom cyano and --SO₃ H,

R₄ signifies hydrogen, C₁₋₈ alkyl, unsubstituted phenyl or phenylsubstituted by one or two substituents selected from halogen, C₁₋₄alkyl, C₁₋₄ alkoxy and --SO₃ H,

R₅ signifies hydrogen, halogen, C₁₋₄ alkyl, C₁₋₄ alkoxy or cyano,##STR2## in which R₆ signifies hydrogen; C₁₋₄ alkyl, unsubstituted orsubstituted by a C₁₋₄ alkyl, C₁₋₄ alkoxy, --SO₃ H, --COOH, C₁₋₄alkoxycarbonyl, aminocarbonyl, mono- or di- C₁₋₄ alkylaminocarbonyl,aminosulphonyl or a mono- or di- C₁₋₄ alkylaminosulphonyl group; orphenyl, unsubstituted or substituted by one or two substituents selectedfrom C₁₋₄ alkyl, C₁₋₄ alkoxy, --SO₃ H, --COOH, C₁₋₄ alkoxycarbonyl,aminocarbonyl, and mono- and di- C₁₋₄ -alkylaminocarbonyl,

R₇ and R₈, independently, each have one of the significances of R₆,above, provided that both do not simultaneously signify an unsubstitutedor substituted phenyl,

R₉ signifies hydrogen; C₁₋₄ alkyl, unsubstituted or substituted by a

i. hydroxy group,

ii. C₁₋₄ alkyl group,

iii. C₁₋₄ alkoxy group, unsubstituted or substituted by a C₁₋₄ alkoxy,--SO₃ H, --COOH, C₁₋₄ alkoxycarbonyl, aminocarbonyl or C₁₋₄ mono- or di-alkylaminocarbonyl group,

iv --SO.sub. 3 H group ##STR3## in which R₁₀ and R₁₁, independently,signify hydrogen or C₁₋₄ alkyl,

vi --COOR.sub. 12 group, in which R₁₂ signifies hydrogen, C₁₋₄ alkyl,unsubstituted or substituted by --SO₃ H, or a phenyl group,unsubstituted or substituted by one or two groups selected from C₁₋₄alkyl and --SO₃ H, ##STR4## in which R₁₃ and R₁₄, independently, eachhave one of the significances of R₁₂, above; provided that both do notsimultaneously signify an unsubstituted or substituted phenyl; a C₂₋₄alkenyl group; a C₁₋₄ alkoxy group; or a phenyl group, unsubstituted orsubstituted by one or two substituents selected from C₁₋₄ alkyl, C₁₋₄alkoxy, --SO₃ H, --COOH, C₁₋₄ alkoxycarbonyl, aminocarbonyl and mono-and di-C₁₋₄ alkylaminocarbonyl radicals;

or U has one of the significances of R₅, above.

As will be appreciated, the compounds of the invention may be in freeacid or salt form. When intended for use as optical brightening agents,as hereinafter described, conventional salt forms such as are used inthe optical brightener art may be employed. In general, the cation inthe salt form may be any non-chromophoric cation. Preferred cations arethe alkali-metal cations, such as of lithium, potassium and sodium,particularly the latter, and ammonium and alkylammonium cations.Preferred such ammonium and alkylammonium cations are of formula R₁₅ R₁₆R₁₇ R₁₈ N.sup.⊕ in which R₁₅, R₁₆, R₁₇ and R₁₈, independently, eachsignify hydrogen or C₁₋₄ alkyl, unsubstituted or substituted by one ortwo, preferably one, hydroxy groups. As examples may be given theammonium, mono-, di- and triethanolammonium and mono-, di- andtri-isopropanolammonium cations. The preferred salt forms are the sodiumsalt forms. As will be appreciated, the salt forms may be obtained fromthe free acid forms, and vice versa, in conventional manner, and furthermay be interconverted in conventional manner. For ease of preparationand for stability considerations, the salt forms of the compounds arepreferred.

In the compounds of the invention, any alkyl or alkoxy radical, wheresuch is of three or more carbon atoms, may be straight or branched. Asexamples of alkyl and alkoxy radicals of 1 to 4 carbon atoms may begiven the methyl, ethyl, n-propyl, iso-propyl, n-butyl and tert.-butylalkyl radicals and the methoxy, ethoxy, n-propoxy, iso-propoxy, n-butoxyand tert.-butoxy alkoxy radicals. As examples of alkyl radicals of 1 to8 carbon atoms may be given the above, together with, for example, thehexyl, heptyl and octyl radicals. Any alkyl radical of 1 to 8 carbonatoms is, however, preferably of 1 to 4 carbon atoms. The more preferredalkyl radicals are the methyl and ethyl radicals, particularly theformer. The preferred alkoxy radicals are the methoxy and ethoxyradicals, particularly the former.

As examples of halogen atoms present in the compounds of the inventionmay be given the fluorine, chlorine and bromine atoms, chlorine beingpreferred.

In the compounds of formula I, R₅ preferably signifies hydrogen. U ispreferably in the p-position of the phenyl ring. U preferably signifiesCN, --CO₂ R₆, --CONR₇ R₈, --SO₂ NR₇ R₈ or --SO₂ R₉, in which R₆, R₇, R₈and R₉ are as defined above. R₁, R₂ and R₃, independently, preferablysignify hydrogen, halogen (particularly chlorine) or C₁₋₄ alkyl(particularly methyl). R₄ preferably signifies hydrogen, C₁₋₄ alkyl orphenyl, more preferably hydrogen.

Thus, as a preferred class of compounds of the invention may be giventhose which, in free acid form, are of formula I' ##STR5## in which R₁', R₂ ' and R₃ ', independently, each signify hydrogen, halogen or C₁₋₄alkyl,

R₄ ' signifies hydrogen, C₁₋₄ alkyl or phenyl, and

U' signifies CN, --CO₂ R₆, --CONR₇ R₈, --SO₂ NR₇ R₈ or --SO₂ R₉, inwhich R₆, R₇, R₈ and R₉ are as defined above.

In the compounds of formula I and I', U and U', respectively, preferablysignify --CO₂ R₆, --SO₂ NR₇ R₈, --SO₂ R₉ or CN. Any R₆ preferablysignifies C₁₋₄ alkyl, particularly C₁₋₂ alkyl. Any R₇ or R₈ in suchgroups or in any group --CONR₇ R₈ is preferably hydrogen or C₁₋₄ alkyl,unsubstituted or substituted by a --SO₃ H group, with the proviso thatonly one --SO₃ H group is borne by the group --CONR₇ R₈ or --SO₂ NR₇ R₈.R₇ and R₈ more preferably both signify hydrogen. Any R₉ in --SO₂ R₉ ispreferably C₁₋₄ alkyl, more preferably methyl or ethyl and mostpreferably methyl. The sulpho group attached to the pyrazoline ring ispreferably in the 4-position thereof and R₄ or R₄ ' preferably in the5-position. R₄ ' in the compounds of formula I' is preferably hydrogen.

As a particularly preferred class of compounds may be given thecompounds which, in free acid form, are of formula I" ##STR6## where R₁", R₂ " and R₃ ", independently, signify hydrogen, chlorine or C₁₋₄alkyl (particularly methyl),

U" signifies CN, --CO₂ R₆ ", --SO₂ NR₇ "R₈ " or --SO₂ R₉ " in which R₆ "signifies C₁₋₄ , preferably C₁₋₂ alkyl, R₇ " and R₈ ", independently,signify hydrogen or C₁₋₄ alkyl, unsubstituted or substituted by a --SO₃H-group, with the proviso that a maximum of one --SO₃ H-group iscontained in --SO₂ NR₇ "R₈ ", R₇ " and R₈ " preferably both signifyinghydrogen, and R₉ " signifies C₁₋₄ alkyl, preferably C₁₋₂ alkyl and morepreferably methyl.

Still further preferred compounds are those which, in free acid form,are of formula I'", ##STR7## in which R₂ '" signifies hydrogen, chlorineor methyl,

R₃ '" signifies hydrogen or methyl, and U'" signifies --CN, --CO₂ R₆ '",--SO₂ NH₂ or --SO₂ R₉ '", in which R₆ '" signifies C₁₋₂ alkyl, and

R₉ '" signifies C₁₋₂ alkyl, preferably methyl.

The most preferred significance of U'" is --SO₂ R₉ '". Also, preferablyR₂ '" and R₃ '" are the same and signify hydrogen or R₂ '" signifieschlorine and R₃ '" signifies methyl.

The invention also provides a process for the production of the1,3-diphenyl 4- or 5-sulpho pyrazolines of the invention, which processcomprises

a. reacting a propiophenone having, or the 2- or 3-position (α or βcarbon atom) a sulpho group, in free acid or salt form, and on the3-position a halogen, free amino, dialkylamino, morpholino, piperidinoor pyrrolidino radical with a phenylhydrazine, or

b. reacting a diphenylnitrile imine (obtainable by treatment of anα-chlorobenzaldehyde phenylhydrazone with base) with a vinyl sulphonicacid in free acid or, preferably, salt form.

More particularly, the invention provides a process for the productionof compounds which, in free acid form, are of formula I, above,characterised by

ai. reacting a compound of formula II, ##STR8## in which R₁, R₂ and R₃are as defined above, and one of R_(x) and R_(y) is SO₃ H, the other R₄,and W signifies a halogen, --NH₂, dialkylamino, morpholino, piperidinoor pyrrolidino radical,

with a compound of formula III, ##STR9## in which R₅ and U are asdefined above, or

bi. reacting a compound of formula IV, ##STR10## with a compound offormula V, ##STR11## in which R₄ is as defined above, and the wavy lineindicates that R₄ may be in cis or trans relative position to the --SO₃H group,

As will be appreciated, interconversions from one compound of theinvention to another are possible. Thus, for example, a compound which,in free acid form, is of formula Ic ##STR12## in which R₁, R₂, R₃, R₄and R₅ are as defined above, and

R₂₀ signifies hydrogen or C₁₋₄ alkyl radical, unsubstituted orsubstituted by a C₁₋₄ alkyl, C₁₋₄ alkoxy, --SO₃ H group, COOH, C₁₋₄alkoxycarbonyl, aminocarbonyl or C₁₋₄ mono or di-alkyl aminocarbonyl,

may be obtained by reacting a compound which, in free acid form, is offormula Id, ##STR13## in which R₁, R₂, R₃, R₄ and R₅ are as definedabove, with a compound of formula VI,

R₂₀ --OH VI

in which R₂₀ is as defined above.

Processes a) and ai) are conveniently carried out in water, in awater-miscible solvent, such as ethanol, iso-propanol, acetic acid ordimethylformamide or in a mixture of water and such solvent. A suitablereaction temperature is from 20° to 200° C., preferably 50° to 150° C.The reaction may be carried out at a pH of from 1 to 10, preferably from4 to 8.

Processes (b) and (bi) are conveniently carried out in an inert organicsolvent, such as cellosolve, or in aqueous organic solvent media, suchas in aqueous cellosolve. A suitable reaction temperature is from 0° to200° C., preferably from 15° to 150° C.

The interconversion, above described for converting a compound offormula Id into a compound of Ic, may be carried out in the presence orabsence of solvents, suitable inert solvents, where such are used, beingdioxan and dimethylformamide. A suitable temperature is from 20° to 150°C., preferably from 20° to 100° C. The reaction is advantageouslycarried out in the presence of a basic catalyst, such as sodiumhydroxide or sodium carbonate.

The compounds of the invention may be isolated and purified inconventional manner.

The compounds of formulae II, III, IV, V and VI, are known or may beobtained in conventional manner from available starting materials. Thecompounds of formula Id are, of course, compounds of the invention and,as such, may be prepared by the processes a) and b) above described.

The compounds of the invention are useful as optical brightening agents,giving good results on natural or synthetic polyamide fibres,particularly on nylon 6 and nylon 6,6 fibres. Thus the invention alsoprovides a process for optically brightening a fibrous substrate,preferably of natural or synthetic polyamide fibres, particularly ofnylon 6 or nylon 6,6 fibres, comprising applying thereto, as brighteningagent, a compound of the invention.

The compounds of the invention may be applied to the polyamide fibres,which may be, for example, in yarn, non-woven, woven or knitted form, inconventional manner, and employing conventional amounts, for example bythe so-called "thermosol" application method, (Gunn and Nightingale"Cotton and Man-Made Fibres Year Book" 1966-67, p. 410).

In such process the compounds are applied in an amount of from 0.01% to0.7%, preferably 0.05% to 0.3%, based on the weight of substrate. Thesubstrate is padded with liquor at a temperature of from 0° to 60° C.,preferably 10° to 50° C. at a pick-up of from 20 to 120%, preferably 40to 90%, the liquor containing such additives as surfactants and formicacid etc. as desired. The subsequent heat treatment applied for 5 to 120secs, preferably 15 to 60 secs, the temperature being 140° to 190° C.,preferably 160° to 185° C., for nylon 6, and 140° to 220° C., preferably170° to 200° C. for nylon 6,6.

The compounds give notably bright effects when applied by this method.Other methods include the so-called "acid flash" procedure and exhaust,acid or neutral bath, methods. In all these applications, the compoundsare preferably employed in salt form.

The following Examples, in which all parts and percentages are by weightand all temperatures are in degrees centigrade, illustrate theinvention.

EXAMPLE 1

17.6 g of the sodium salt of 4'-chloroacetophenone-2-sulphonic acid(Zhur. Obshchei Khim., 29, 949 [1959] ), 9.3 g morpholine hydrochlorideand 2.3 g paraformaldehyde were added to 60 ml cellosolve. The mixturewas refluxed for 1 hour, cooled to 0° and the white precipitatecollected by filtration to give 21.6 g of the Mannich base (internalsalt).

21.6 g of the crude Mannich base, 12.6 g ofp-sulphonamidophenylhydrazine hydrochloride (Gazz. chim. ital. 72, 97[1942] ) and 17.0 g sodium carbonate were added to 150 ml water. Themixture was refluxed for 3 hours, cooled to 0° and the yellow solidcollected by filtration. The filter cake was washed and dried to givethe pyrazoline: ##STR14## as a pale yellow solid.

EXAMPLE 2

8.68 g3-(4"-morpholino)-[4'-chloro-2',5'-dimethylpropiophenone]-2-sulphonate(internal salt - prepared by an analogous procedure to that for thepreparation of the Mannich base in Example 1), 4.5 gp-hydrazinophenyl-methyl-sulphone (Belg. Pat. No. 666,407; J. Prakt.Chem. 132, 24 [1931]) and 1.27 g sodium carbonate were added to 40 mlwater. The mixture was refluxed for 17 hours, cooled to 0° and theyellow solid collected by filtration. The filter cake was washed anddried to give the pyrazoline: ##STR15## as a white solid.

EXAMPLE 3

By repeating the procedure of Example 1, but usingp-hydrazinophenyl-methyl sulphone, the pyrazoline: ##STR16## wasobtained as a pale yellow solid.

EXAMPLE 4

By repeating the procedure of Example 2, but usingp-sulphonamidophenylhydrazine hydrochloride, the pyrazoline: ##STR17##was obtained as a white solid.

EXAMPLE 5

To a solution of 21.6 g α-chlorobenzaldehyde phenylhydrazone (Ber., 27,2121 [1894] ) and 19.5 g sodium vinyl sulphonate in 300 ml cellosolveand 45 ml water was added 27.5 ml tri-ethylamine at 25°. The resultingmixture was stirred at room temperature for 24 hours, filtered and thesolvent removed from the filtration to give the pyrazoline: ##STR18## asa pale yellow solid.

By repeating the procedures of Example 1 or 2, using the appropriatestarting materials, the following pyrazolines were obtained:

    __________________________________________________________________________    Expl.                                                                         No. Compound                     Appearance                                   __________________________________________________________________________         ##STR19##                   Pale yellow  solid                           7                                                                                  ##STR20##                   Pale yellow  solid                           8                                                                                  ##STR21##                   Pale yellow  solid                           __________________________________________________________________________

EXAMPLE 9

28.65 g3-(4"-morpholino)-(4',5-dichloro-2'-methylpropiophenone)-2-sulphonate(internal salt - prepared by an analogous procedure to that for thepreparation of the Mannich base in Example 1, above, 15.81 gp-hydrazino-phenyl-methyl-sulphone and 4.25 g sodium carbonate wereadded to 110 ml water, the mixture was refluxed for 4 hours, cooled to0° C. and the yellow solid collected by filtration. The filter cake waswashed and dried to give the pyrazoline: ##STR22## as a pale yellowsolid.

EXAMPLE 10

By repeating the procedure of Example 9, but using p-sulphonamido phenylhydrazine hydrochloride, the pyrazoline: ##STR23## was obtained as apale yellow solid.

EXAMPLE 11

By repeating the procedure of Example 1, above, but using p-cyanophenylhydrazine hydrochloride (J. Amer. Chem. Soc., 66 1851, (1944), thepyrazoline: ##STR24## was obtained as a pale yellow solid.

Following the procedure of Example 1 or Example 2 and employingappropriate starting materials, the following compounds are obtained.

    __________________________________________________________________________    Example                                                                            Compound                         Appearance                              __________________________________________________________________________    12                                                                                  ##STR25##                       pale yellow solid                       13                                                                                  ##STR26##                       off white solid                         14                                                                                  ##STR27##                       off white solid                         15                                                                                  ##STR28##                       pale yellow solid                       16                                                                                  ##STR29##                       yellow solid                            17                                                                                  ##STR30##                       pale yellow solid                       18                                                                                  ##STR31##                       white solid                             19                                                                                  ##STR32##                       off white solid                         __________________________________________________________________________

EXAMPLE 20

By repeating the procedure of Example 5, but usingα-chloro-p-chlorobenzaldehyde-p-methylsulphonyl-phenylhydrazone(prepared by an analogous procedure to that for the preparation ofα-chlorobenzaldehyde phenylhydrazone) the pyrazoline: ##STR33## wasobtained as a yellow solid.

EXAMPLE 21

By repeating the procedure of Example 1, but using3-(4"-morpholino)-propiophenone-2-sulphonate (prepared by an analogousprocedure to that for the preparation of the Mannich base in thatexample) and p-hydrazino methylbenzoate, the pyrazoline: ##STR34## wasobtained as a pale yellow solid.

EXAMPLE 22

By repeating the procedure of Example 22, but using phenyl hydrazine,the pyrazoline: ##STR35## was obtained as a pale yellow solid.

EXAMPLE 23

By repeating the procedure of Example 21, but replacing the sodium vinylsulphonate used therein by 1-sulpho-prop-1-ene sodium salt, thepyrazoline: ##STR36## was obtained as a pale yellow solid.

APPLICATION EXAMPLES

A. A strip of white nylon 6,6, 15 cm wide and weighing 8 g, was paddedat 100% expression through a solution containing 0.2% of the pyrazolineproduced in Example 3, 2% of a non-ionic alkylene oxide adduct of analkylated phenol, and 0.2% formic acid. The nylon piece was dried at 80°and then passed through an oven at 180° for 30 seconds. The treatedpiece showed a brilliant whiteness of neutral hue, compared with theuntreated piece.

B. A strip of white nylon 6, 15 cm wide and weighing 8 g, was padded at100% expression through a solution containing 0.1% of the pyrazolineproduced in Example 3, above, and 0.2% formic acid. The nylon piece wasdried at 80° and then passed through an oven at 180° for 30 seconds. Thetreated piece showed a brilliant whiteness of neutral hue, compared withthe untreated piece.

C. A strip of nylon 6.6, 15 cm wide and weighing 8 g, was padded at 100%expression through a solution containing 0.1% of the pyrazoline producedin Example 7, above. The nylon piece was boiled for 1 minute in 240 mlwater containing 0.2% acetic acid, and was then washed off in boilingwater for 1 minute. The piece was then rinsed in cold demineralisedwater and dried in an oven at 80°. The treated piece showed a brilliantwhiteness compared to the untreated piece.

D. A 5 g piece of white nylon 6.6 was treated with 200 ml of a solutioncontaining 25 milligrams of the pyrazoline produced in Example 9, above,and 150 ml of glacial acetic acid. The piece was entered at 40°, thetemperature of the bath increased to 90°-100° over 30 minutes and thenmaintained at 90°-100° for a further 30 minutes. The piece was removedfrom the bath, rinsed in cold demineralised water and dried in an ovenat 80°. The treated piece showed a brilliant whiteness compared to theuntreated piece.

What is claimed is:
 1. A compound of the formula: ##STR37## wherein R₁', R₂ ' and R₃ ', independently, are hydrogen, halogen or C₁₋₄ alkyl,R₄' is hydrogen, C₁₋₄ alkyl or phenyl, and U' is --COOR₆, --CONH₂, SO₂ R₉or SO₂ NH₂ where R₆ and R₉ are C₁₋₄ alkyl.
 2. A compound according toclaim 1 wherein U' is --SO₂ R₉ or SO₂ NH₂.
 3. A compound of claim 1,wherein U' signifies --SO₂ NH₂ or --CONH₂.
 4. A compound of claim 1,wherein U' signifies --CO₂ R₆.
 5. A compound of claim 4, wherein R₆ isC₁₋₂ alkyl.
 6. A compound of claim 1, wherein U' signifies --SO₂ R₉. 7.A compound of claim 6, wherein R₉ is C₁₋₂ alkyl.
 8. A compound of claim1, wherein R₄ ', signifies hydrogen.
 9. A compound of claim 8, whereinU' signifies --SO₂ NH₂ or --SO₂ R₉.
 10. A compound of claim 9, whereinR₂ ' signifies a chlorine atom in the 4-position of the phenyl ring towhich it is attached, R₁ ' signifies a methyl group in the 2-position ofsaid phenyl ring, or hydrogen, and R₃ ' signifies a chlorine atom in the5-position of said phenyl ring, or hydrogen.
 11. A compound according toclaim 9, wherein U' is --SO₂ R₉.
 12. A compound of claim 8, which, infree acid form, is of formula I", ##STR38## wherein R₁ ", R₂ " and R₃ ",independently, signify hydrogen, chlorine or C₁₋₄ alkyl,U" is CO₂ R₆,SO₂ NH₂ or SO₂ R₉.
 13. A compound of claim 12, wherein any C₁₋₄ alkyl asR₁ ", R₂ " or R₃ " is methyl.
 14. A compound of claim 13, wherein anyC₁₋₄ alkyl as R₆ or R₉ is C₁₋₂ alkyl.
 15. A compound of claim 14, which,in free acid form, is of formula I'", ##STR39## in which R₂ '" signifieshydrogen, chlorine or methyl,R₃ '" signifies hydrogen or methyl, and U"signifies --CN, --CO₂ R₆ '", --SO₂ NH₂ or --SO₂ R₉ '", in which R₆ '"signifies C₁₋₂ alkyl, and R₉ '" signifies C₁₋₂ alkyl.
 16. A compound ofclaim 15, wherein U" signifies --SO₂ R₉.
 17. A compound of claim 16,wherein R₉ signifies methyl.
 18. A compound of claim 17, wherein eitherR₂ '" and R₃ '" are the same and signify hydrogen, or R₂ '" signifieschlorine and R₃ '" signifies methyl.
 19. A compound of claim 18, which,in free acid form, is of formula ##STR40##
 20. A compound of claim 18,which, in free acid form, is of formula ##STR41##
 21. A compound ofclaim 1, in salt form.
 22. A compound of claim 21, in alkali-metal,ammonium or alkylammonium salt form.
 23. A compound of claim 22, whereinany ammonium or alkylammonium cation is of the formula R₁₅ R₁₆ R₁₇ R₁₈N.sup.⊕, where R₁₅, R₁₆, R₁₇ and R₁₈, independently, signify hydrogen orC₁₋₄ alkyl, unsubstituted or substituted by one or two hydroxy groups.24. A compound of claim 22, in sodium salt form.